Definify.com
Webster 1913 Edition
Tail-bay
Tail′-bayˊ
,Noun.
1.
(Arch.)
One of the joists which rest one end on the wall and the other on a girder; also, the space between a wall and the nearest girder of a floor. Cf.
Case-bay
. 2.
The part of a canal lock below the lower gates.